In situ hybridization has been a major research tool for molecular geneticists to visualize specific DNA or RNA sequences present in cells. Originally performed in an isotopic format, non-isotopic techniques, such as fluorescence in situ hybridization (FISH), are rapidly becoming the method of choice, because they can be accomplished faster, multiple signals can be detected at one time and hybridization signals can be more precisely located.
In general, however, non-isotopic methods have suffered from a lack of sensitivity, especially if the samples to be analyzed include dead and/or degrading cells. Dead or degrading cells appear to be resistant to in situ hybridization, possibly because the nuclear DNA itself has begun to degrade and/or because the cells do not respond to the chemical reagents used in processing. The presence within a sample of cells which are resistant to in situ hybridization makes the analysis of any informative cells, which may also be present, difficult.
A method for preferentially isolating informative cells which produce clear hybridization signals in an in situ hybridization assay would be useful.